Cooling device for a light source in a copying machine

ABSTRACT

A cooling device is provided for a light source in a copying machine, wherein the generation of air seemingly waving due to heat is prevented by effectively cooling a lamp body for lighting an original effectively in order to obviate the deterioration of an optical image. 
     Light pervious heat-shield members are disposed at suitable intervals in an irradiation opening of the lamp body accommodating light source bulb and a reflector therewithin so as to enable blowing of ambient air past and between these members. At least the member positioned at the side of the light source bulb is composed of a heat-ray absorption glass. Air flow is guided through the chamber accommodating the light source bulb so that it may perform a forced air cooling of the inside of the lamp body in order to prevent the generation of the air waving due to heat from the lamp.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a cooling device for a light source ina copying machine, and in particular to a cooling technology for alighting device composed of a light source bulb and a reflectoraccommodated within a lamp body.

Generally, a high grade bright lamp such as a halogen lamp is utilizedfor lighting an original in a copying machine. However, such a brightlamp also radiates much heat, and elements near the lamp are apt tosuffer from the resultant high temperature.

A known cooling device for a light source in a copying machine, asdisclosed in Japanese Provisional Patent Publication No. 136322 of 1979,for example is so constructed that a duct-like lamp body whichaccommodates a long curved reflector and a light source bulb therein isprovided with an irradiation opening and a filter that is pervious tolight but blocking infrared rays. The air heated by the light source isremoved by blowing air into the body so as to also cool the light sourcebulb.

However, since the filter that is a light-pervious heat-shield member iscooled only at the inside and the heat accumulated in it is radiatedfrom its outer surface, elements near the filter can not be preventedfrom being heated thereby.

The heated air around the filter is therefore apt to appear waving withthe heat radiated from the filter. When the seemingly waving air isextends into the light path focusing an image, in the optical system ofthe copying machine, the copied image is likely to be reproduced out offocus owing to the image focus being deteriorated by the "waving" heatedair.

DISCLOSURE OF THE INVENTION

The present invention is directed to solving the problems noted above,and has for its object to provide a cooling device for a light source ina copying machine, which is able to prevent the presence of heated airwaving around the filter.

In a preferred embodiment of the cooling device of the present inventionfor accomplishing the above purpose, light-pervious heat-shield membersare disposed at suitable intervals in an irradiation opening of a lampbody accommodating a light source bulb and a reflector therewithin, soas allow blowing of ambient air past these members. At least the memberspositioned at the side of the light source bulb are composed of aheat-ray absorption glass. Accordingly, the cooling device dischargesambient air blown past these members of the lamp body through thechamber accommodating the light source bulb, so that this blown air mayperform a forced cooling of the inside of the lamp body to prevent thegeneration of the air waving with heat.

According to the present invention, since those light-perviousheat-shield members are disposed at suitable intervals in theirradiation opening of the lamp body so as to enable blowing of ambientair for cooling into among these members and provide air layers betweeneach pair of them, the heat transfer to outside members is prevented bythese air layers and each pair of members is cooled effectively by thecooling air flow passing therethrough. Since the light-perviousheat-shield member at the light source side is composed of a heat-rayabsorption glass, heat rays radiated linearly from the light source bulband the reflector are absorbed and accumulated by the glass and heat isthen radiated from the glass. This heat is removed by the cooling airflow passing through the space outside and thus the heat transfer to theoutside members is blocked effectively. Further, since the cooling airflow passed through the spaces among the members is discharged throughthe chamber (which contains the light source bulb within the lamp body),the chamber is also cooled effectively. Hence other optical elementsthat should not be subjected to the heat radiation from the the lampbody are also kept cool.

The foregoing and other objects and attendant advantages of the presentinvention will be readily appreciated as the same become betterunderstood by reference to the following detailed description whenconsidered with the accompanying drawings, wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical sectional view of a lamp body of a preferedembodiment of the present invention.

FIG. 2 is a perspective view of an electrophotographic copying machineaccording to the present invention.

FIG. 3 is a schematic sectional view on line X--X in FIG. 2.

DESCRIPTION OF THE PREFERED EMBODIMENT

As shown in FIGS. 2 and 3, a typical electrophotographic copying machinecomprises an operation panel 1 at the center of its front side, originalfeeding and scanning equipment 2 at its left side and reproduced imagerecording equipment 3 at its right side. In the original feeding andscanning equipment 2, when an original with an image facing onto anoriginal setter 4 is fed into the equipment it is carried by feedrollers 5 and carriage rollers 6 while being lighted by an originallighting device 7 on its way to an original receptacle.

While the original is being carried on this pathway, the image of theoriginal is exposed in focus through a slit onto a photosensitive drum(not shown in Figures) by a focussing optical system 11 composed of apair of mirrors 9 and a lens 10 so as to produce a latent image thereon.Then the latent image is made visible by means of a toner developmentdevice (not shown) and is transferred onto a sheet of recording paper asa toner image in the recording equipment 3.

The original lighting device 7 includes a pair of lamp bodies 13a and13b, arranged in the front and in the rear at a right angle to anoriginal carrying direction under an original carrying pathway 12 formedby the feed rollers 5 and the carriage rollers 6. Both lamp bodies 13aand 13b are thus disposed in the front and in the rear, respectively,across the optical axis of the focusing optical system centeredtherebetween, so that their irradiations are directed to cross theoriginal carrying pathway 12 in its plane and towards an elongaterectangular region crossing at right angles to the optical axis.

As each of the lamp bodies has the same construction, only theconstruction of the rear lamp body 13b is explained hereinafter, withreference to FIG. 1.

The lamp body 13b comprises a duct-like casing 15 provided with anirradiation opening 14 at the upper wall, a long curved reflector 16fixed in the casing 15 and a plurality of straight tubular halogen lamps17 as a light source arranged in series longitudinally at the inside ofthe curved reflector 16.

In the irradiation opening 14 of the casing 15, there is provided asupporting framework 20 for a heat-shield member which supports a heatresistance glass 18 and a heat-ray absorption glass 19, respectivelyabove and below at suitable intervals. A space for a cooling air flowpassage 21 is formed by the surrounding walls of the supportingframework 20 and both glass elements 18 and 19 positioned above andbelow, respectively. The cooling air flow passage 21 communicates with achamber 22 accommodating the light source bulb through manycommunication holes 23. The chamber 22 communicates with the outside ofthe casing 15 through cooling air outlets 24 provided in the casing 15,and the passage 21 also communicates with the outside through coolingair inlets 25. The longitudinal side walls of the lamp body 13b areprovided with many cooling air inlets 25 in zigzags, and the transverseside walls are provided with the inlets 25 of elongated holes as shownin FIG. 1. These cooling air inlets 25 are so communicated with adelivery portion of a blower (not shown) that ambient air for coolingmay be supplied forcedly into the lamp body 13b, so as to cool not onlythe heat resistance glass 18 and the heat absorption glass 19 but alsothe chamber 22 accommodating the light source bulb and the bulb itself.

Further, the cooling air outlets 24 may be connected to a suction sideof an induced draft fan (not shown) so as to make the inside of the lampbody forcedly air-cooled. Also, a heat-ray absorption glass may beutilized instead of the heat resistance glass in the irradiationopening. Still further, two plates of glass may be arranged so as toform dual cooling air flow passage.

As described above, since a cooling device according to the presentinvention is provided with light-pervious heat-shield members atsuitable intervals in an opening of a lamp body accommodating areflector and a light source bulb, at least the member at the bulb sideof which is composed of a heat-ray absorption glass, so as to passambient air for cooling through the members, the heat rays radiated fromthe light source bulb can be absorbed by the heat-ray absorption glassto prevent the heat rays from being radiated to the outside of the lampbody. Further, since the light-pervious heat-shield members are arrangedin multiplex state to cool them by ambient air supplied therebetween,the heat transfer to the outer members is blocked in order to lessensubstantially the heat rays radiated from the outer members.Consequently, since the air-waving is thus eliminated near the lampbody, especially near the upper surface of the upper glass member, areproduced image can be sharpened and made distinct.

On the other hand, when the cooling air supplied to flow among themultiplex light-pervious heat-shield members is discharged to theoutside of the lamp body through the chamber accommodating the lightsource bulb, the durability of the light source bulb can be improvedsubstantially by the forced air cooling for the bulb.

We claim:
 1. A cooling device for a light source in a copying machine,which comprises:a lamp body accommodating a reflector and a light sourcebulb therewithin, said lamp body being formed with plural cooling airinlets, outlets and communication holes; an irradiation opening providedat the part of said lamp body opposite to said reflector; and aplurality of light-pervious heat-shield members arranged at suitableintervals in said irradiation opening, with at least the light-perviousheat-shield members positioned at the side of said light source bulbamong said members being composed of a heat-ray absorption glass;whereby space formed between each pair of said members communicates withthe outside of said lamp body through said cooling air inlets, saidspace being communicated with a chamber accommodating said light sourcebulb through said communication holes and said chamber accommodatingsaid bulb being communicated with said outside of said lamp body throughsaid cooling air outlets to enable the flow of cooling air supplied fromsaid outside of said lamp body to be passed in turn through said spacebetween said members and through said chamber and then to be dischargedto said outside, for forced air cooling of the inside of said lamp body.2. A cooling device for a light source according to claim 1, furthercomprising:a blower to provide said cooling flow.
 3. A cooling devicefor a light source according to claim 1, further comprising:a fan forapplying suction to generate said cooling air flow.